1 // Copyright 2011 Google Inc. All Rights Reserved.
2 //
3 // Use of this source code is governed by a BSD-style license
4 // that can be found in the COPYING file in the root of the source
5 // tree. An additional intellectual property rights grant can be found
6 // in the file PATENTS. All contributing project authors may
7 // be found in the AUTHORS file in the root of the source tree.
8 // -----------------------------------------------------------------------------
9 //
10 // Selecting filter level
11 //
12 // Author: somnath@google.com (Somnath Banerjee)
13
14 #include <assert.h>
15 #include "./vp8enci.h"
16 #include "../dsp/dsp.h"
17
18 // This table gives, for a given sharpness, the filtering strength to be
19 // used (at least) in order to filter a given edge step delta.
20 // This is constructed by brute force inspection: for all delta, we iterate
21 // over all possible filtering strength / thresh until needs_filter() returns
22 // true.
23 #define MAX_DELTA_SIZE 64
24 static const uint8_t kLevelsFromDelta[8][MAX_DELTA_SIZE] = {
25 { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
26 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
27 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
28 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63 },
29 { 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 17, 18,
30 20, 21, 23, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 42,
31 44, 45, 47, 48, 50, 51, 53, 54, 56, 57, 59, 60, 62, 63, 63, 63,
32 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
33 { 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 16, 17, 19,
34 20, 22, 23, 25, 26, 28, 29, 31, 32, 34, 35, 37, 38, 40, 41, 43,
35 44, 46, 47, 49, 50, 52, 53, 55, 56, 58, 59, 61, 62, 63, 63, 63,
36 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
37 { 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 15, 16, 18, 19,
38 21, 22, 24, 25, 27, 28, 30, 31, 33, 34, 36, 37, 39, 40, 42, 43,
39 45, 46, 48, 49, 51, 52, 54, 55, 57, 58, 60, 61, 63, 63, 63, 63,
40 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
41 { 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 14, 15, 17, 18, 20,
42 21, 23, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 42, 44,
43 45, 47, 48, 50, 51, 53, 54, 56, 57, 59, 60, 62, 63, 63, 63, 63,
44 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
45 { 0, 1, 2, 4, 5, 7, 8, 9, 11, 12, 13, 15, 16, 17, 19, 20,
46 22, 23, 25, 26, 28, 29, 31, 32, 34, 35, 37, 38, 40, 41, 43, 44,
47 46, 47, 49, 50, 52, 53, 55, 56, 58, 59, 61, 62, 63, 63, 63, 63,
48 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
49 { 0, 1, 2, 4, 5, 7, 8, 9, 11, 12, 13, 15, 16, 18, 19, 21,
50 22, 24, 25, 27, 28, 30, 31, 33, 34, 36, 37, 39, 40, 42, 43, 45,
51 46, 48, 49, 51, 52, 54, 55, 57, 58, 60, 61, 63, 63, 63, 63, 63,
52 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
53 { 0, 1, 2, 4, 5, 7, 8, 9, 11, 12, 14, 15, 17, 18, 20, 21,
54 23, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 42, 44, 45,
55 47, 48, 50, 51, 53, 54, 56, 57, 59, 60, 62, 63, 63, 63, 63, 63,
56 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 }
57 };
58
VP8FilterStrengthFromDelta(int sharpness,int delta)59 int VP8FilterStrengthFromDelta(int sharpness, int delta) {
60 const int pos = (delta < MAX_DELTA_SIZE) ? delta : MAX_DELTA_SIZE - 1;
61 assert(sharpness >= 0 && sharpness <= 7);
62 return kLevelsFromDelta[sharpness][pos];
63 }
64
65 //------------------------------------------------------------------------------
66 // Paragraph 15.4: compute the inner-edge filtering strength
67
GetILevel(int sharpness,int level)68 static int GetILevel(int sharpness, int level) {
69 if (sharpness > 0) {
70 if (sharpness > 4) {
71 level >>= 2;
72 } else {
73 level >>= 1;
74 }
75 if (level > 9 - sharpness) {
76 level = 9 - sharpness;
77 }
78 }
79 if (level < 1) level = 1;
80 return level;
81 }
82
DoFilter(const VP8EncIterator * const it,int level)83 static void DoFilter(const VP8EncIterator* const it, int level) {
84 const VP8Encoder* const enc = it->enc_;
85 const int ilevel = GetILevel(enc->config_->filter_sharpness, level);
86 const int limit = 2 * level + ilevel;
87
88 uint8_t* const y_dst = it->yuv_out2_ + Y_OFF;
89 uint8_t* const u_dst = it->yuv_out2_ + U_OFF;
90 uint8_t* const v_dst = it->yuv_out2_ + V_OFF;
91
92 // copy current block to yuv_out2_
93 memcpy(y_dst, it->yuv_out_, YUV_SIZE * sizeof(uint8_t));
94
95 if (enc->filter_hdr_.simple_ == 1) { // simple
96 VP8SimpleHFilter16i(y_dst, BPS, limit);
97 VP8SimpleVFilter16i(y_dst, BPS, limit);
98 } else { // complex
99 const int hev_thresh = (level >= 40) ? 2 : (level >= 15) ? 1 : 0;
100 VP8HFilter16i(y_dst, BPS, limit, ilevel, hev_thresh);
101 VP8HFilter8i(u_dst, v_dst, BPS, limit, ilevel, hev_thresh);
102 VP8VFilter16i(y_dst, BPS, limit, ilevel, hev_thresh);
103 VP8VFilter8i(u_dst, v_dst, BPS, limit, ilevel, hev_thresh);
104 }
105 }
106
107 //------------------------------------------------------------------------------
108 // SSIM metric
109
110 enum { KERNEL = 3 };
111 static const double kMinValue = 1.e-10; // minimal threshold
112
VP8SSIMAddStats(const DistoStats * const src,DistoStats * const dst)113 void VP8SSIMAddStats(const DistoStats* const src, DistoStats* const dst) {
114 dst->w += src->w;
115 dst->xm += src->xm;
116 dst->ym += src->ym;
117 dst->xxm += src->xxm;
118 dst->xym += src->xym;
119 dst->yym += src->yym;
120 }
121
VP8SSIMAccumulate(const uint8_t * src1,int stride1,const uint8_t * src2,int stride2,int xo,int yo,int W,int H,DistoStats * const stats)122 static void VP8SSIMAccumulate(const uint8_t* src1, int stride1,
123 const uint8_t* src2, int stride2,
124 int xo, int yo, int W, int H,
125 DistoStats* const stats) {
126 const int ymin = (yo - KERNEL < 0) ? 0 : yo - KERNEL;
127 const int ymax = (yo + KERNEL > H - 1) ? H - 1 : yo + KERNEL;
128 const int xmin = (xo - KERNEL < 0) ? 0 : xo - KERNEL;
129 const int xmax = (xo + KERNEL > W - 1) ? W - 1 : xo + KERNEL;
130 int x, y;
131 src1 += ymin * stride1;
132 src2 += ymin * stride2;
133 for (y = ymin; y <= ymax; ++y, src1 += stride1, src2 += stride2) {
134 for (x = xmin; x <= xmax; ++x) {
135 const int s1 = src1[x];
136 const int s2 = src2[x];
137 stats->w += 1;
138 stats->xm += s1;
139 stats->ym += s2;
140 stats->xxm += s1 * s1;
141 stats->xym += s1 * s2;
142 stats->yym += s2 * s2;
143 }
144 }
145 }
146
VP8SSIMGet(const DistoStats * const stats)147 double VP8SSIMGet(const DistoStats* const stats) {
148 const double xmxm = stats->xm * stats->xm;
149 const double ymym = stats->ym * stats->ym;
150 const double xmym = stats->xm * stats->ym;
151 const double w2 = stats->w * stats->w;
152 double sxx = stats->xxm * stats->w - xmxm;
153 double syy = stats->yym * stats->w - ymym;
154 double sxy = stats->xym * stats->w - xmym;
155 double C1, C2;
156 double fnum;
157 double fden;
158 // small errors are possible, due to rounding. Clamp to zero.
159 if (sxx < 0.) sxx = 0.;
160 if (syy < 0.) syy = 0.;
161 C1 = 6.5025 * w2;
162 C2 = 58.5225 * w2;
163 fnum = (2 * xmym + C1) * (2 * sxy + C2);
164 fden = (xmxm + ymym + C1) * (sxx + syy + C2);
165 return (fden != 0.) ? fnum / fden : kMinValue;
166 }
167
VP8SSIMGetSquaredError(const DistoStats * const s)168 double VP8SSIMGetSquaredError(const DistoStats* const s) {
169 if (s->w > 0.) {
170 const double iw2 = 1. / (s->w * s->w);
171 const double sxx = s->xxm * s->w - s->xm * s->xm;
172 const double syy = s->yym * s->w - s->ym * s->ym;
173 const double sxy = s->xym * s->w - s->xm * s->ym;
174 const double SSE = iw2 * (sxx + syy - 2. * sxy);
175 if (SSE > kMinValue) return SSE;
176 }
177 return kMinValue;
178 }
179
VP8SSIMAccumulatePlane(const uint8_t * src1,int stride1,const uint8_t * src2,int stride2,int W,int H,DistoStats * const stats)180 void VP8SSIMAccumulatePlane(const uint8_t* src1, int stride1,
181 const uint8_t* src2, int stride2,
182 int W, int H, DistoStats* const stats) {
183 int x, y;
184 for (y = 0; y < H; ++y) {
185 for (x = 0; x < W; ++x) {
186 VP8SSIMAccumulate(src1, stride1, src2, stride2, x, y, W, H, stats);
187 }
188 }
189 }
190
GetMBSSIM(const uint8_t * yuv1,const uint8_t * yuv2)191 static double GetMBSSIM(const uint8_t* yuv1, const uint8_t* yuv2) {
192 int x, y;
193 DistoStats s = { .0, .0, .0, .0, .0, .0 };
194
195 // compute SSIM in a 10 x 10 window
196 for (x = 3; x < 13; x++) {
197 for (y = 3; y < 13; y++) {
198 VP8SSIMAccumulate(yuv1 + Y_OFF, BPS, yuv2 + Y_OFF, BPS, x, y, 16, 16, &s);
199 }
200 }
201 for (x = 1; x < 7; x++) {
202 for (y = 1; y < 7; y++) {
203 VP8SSIMAccumulate(yuv1 + U_OFF, BPS, yuv2 + U_OFF, BPS, x, y, 8, 8, &s);
204 VP8SSIMAccumulate(yuv1 + V_OFF, BPS, yuv2 + V_OFF, BPS, x, y, 8, 8, &s);
205 }
206 }
207 return VP8SSIMGet(&s);
208 }
209
210 //------------------------------------------------------------------------------
211 // Exposed APIs: Encoder should call the following 3 functions to adjust
212 // loop filter strength
213
VP8InitFilter(VP8EncIterator * const it)214 void VP8InitFilter(VP8EncIterator* const it) {
215 if (it->lf_stats_ != NULL) {
216 int s, i;
217 for (s = 0; s < NUM_MB_SEGMENTS; s++) {
218 for (i = 0; i < MAX_LF_LEVELS; i++) {
219 (*it->lf_stats_)[s][i] = 0;
220 }
221 }
222 }
223 }
224
VP8StoreFilterStats(VP8EncIterator * const it)225 void VP8StoreFilterStats(VP8EncIterator* const it) {
226 int d;
227 VP8Encoder* const enc = it->enc_;
228 const int s = it->mb_->segment_;
229 const int level0 = enc->dqm_[s].fstrength_; // TODO: ref_lf_delta[]
230
231 // explore +/-quant range of values around level0
232 const int delta_min = -enc->dqm_[s].quant_;
233 const int delta_max = enc->dqm_[s].quant_;
234 const int step_size = (delta_max - delta_min >= 4) ? 4 : 1;
235
236 if (it->lf_stats_ == NULL) return;
237
238 // NOTE: Currently we are applying filter only across the sublock edges
239 // There are two reasons for that.
240 // 1. Applying filter on macro block edges will change the pixels in
241 // the left and top macro blocks. That will be hard to restore
242 // 2. Macro Blocks on the bottom and right are not yet compressed. So we
243 // cannot apply filter on the right and bottom macro block edges.
244 if (it->mb_->type_ == 1 && it->mb_->skip_) return;
245
246 // Always try filter level zero
247 (*it->lf_stats_)[s][0] += GetMBSSIM(it->yuv_in_, it->yuv_out_);
248
249 for (d = delta_min; d <= delta_max; d += step_size) {
250 const int level = level0 + d;
251 if (level <= 0 || level >= MAX_LF_LEVELS) {
252 continue;
253 }
254 DoFilter(it, level);
255 (*it->lf_stats_)[s][level] += GetMBSSIM(it->yuv_in_, it->yuv_out2_);
256 }
257 }
258
VP8AdjustFilterStrength(VP8EncIterator * const it)259 void VP8AdjustFilterStrength(VP8EncIterator* const it) {
260 VP8Encoder* const enc = it->enc_;
261 if (it->lf_stats_ != NULL) {
262 int s;
263 for (s = 0; s < NUM_MB_SEGMENTS; s++) {
264 int i, best_level = 0;
265 // Improvement over filter level 0 should be at least 1e-5 (relatively)
266 double best_v = 1.00001 * (*it->lf_stats_)[s][0];
267 for (i = 1; i < MAX_LF_LEVELS; i++) {
268 const double v = (*it->lf_stats_)[s][i];
269 if (v > best_v) {
270 best_v = v;
271 best_level = i;
272 }
273 }
274 enc->dqm_[s].fstrength_ = best_level;
275 }
276 } else if (enc->config_->filter_strength > 0) {
277 int max_level = 0;
278 int s;
279 for (s = 0; s < NUM_MB_SEGMENTS; s++) {
280 VP8SegmentInfo* const dqm = &enc->dqm_[s];
281 // this '>> 3' accounts for some inverse WHT scaling
282 const int delta = (dqm->max_edge_ * dqm->y2_.q_[1]) >> 3;
283 const int level =
284 VP8FilterStrengthFromDelta(enc->filter_hdr_.sharpness_, delta);
285 if (level > dqm->fstrength_) {
286 dqm->fstrength_ = level;
287 }
288 if (max_level < dqm->fstrength_) {
289 max_level = dqm->fstrength_;
290 }
291 }
292 enc->filter_hdr_.level_ = max_level;
293 }
294 }
295
296 // -----------------------------------------------------------------------------
297